The present invention relates to an improved security fastener having a multi-tier drive.
There are numerous types of security fasteners known. Many of these security fasteners include an undulating groove or ridge which receives a mating key. However, fasteners of these types require the groove or ridge to have sufficient axial length so as to provide a relatively large area of contact with a mating key which is required to turn them. The greater the axial length, the greater will be the ability of unauthorized tools to turn the fasteners. Additionally, fasteners having a relatively long axial length are fabricated by complex machining operations which increases their costs.